The overall goal of these studies is the devleopment of two in vitro transformation assays for the evaluation of chemopreventive agents. The two systems utilize primary Syrian hamster embryo cells and retroviral-infected Fischer rat embryo cells (a continuous cell culture). Both cell types are routinely transformed by carcinogenic chemicals with the anchorage-independent growth end point associated with tumorigenicity. Model chemopreventive agents (inhibitors of prostaglandin synthesis and protease inhibitors) will be used to inhibit transformation by chemical carcinogens. Conditions for maximum effectiveness of the selected chemopreventive agents will be established during Phase I. During Phase II the use of fluorescent antibodies to oncogene products will be investigated as a means of detecting the emergence of malignant cells earlier than is seen by colony formation in soft agarose. This will allow an even more effective means of evaluating chemopreventive agents.